How does the j2objc code translator work?

Question

Java

Tell me, there is a ready-made debugged Java application (actually for android), the functionality is something like this: client-server, loading new objects, displaying them on a map.
It is necessary to release it for ios, I would not like to write from scratch (order, because I can’t master it myself).
The other day I read about j2objc, as far as I understand, it translates code from Java to Objective-C, and the output is working code (everything except the interface), is that right?